Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended				1 Months Ended					1 Months Ended
	Oct. 31, 2012	Oct. 31, 2012 Maximum	Oct. 31, 2012 Claims Incurred After November 1, 2002 Maximum	Oct. 31, 2012 Effective date starting after October 31,2012	Oct. 17, 2012 Bojorquez	May 17, 2012 Bojorquez	Jul. 31, 2012 Augustus Claim	Feb. 08, 2012 Augustus	Oct. 31, 2012 Augustus	Jul. 31, 2012 Augustus Motion against others
Loss Contingencies [Line Items]
Surety Bonds	$ 297,500,000			$ 40,400,000
Total letters of credit	105,200,000
Deductible directors' and officers' insurance		5,000,000	1,000,000
Loss contingency amount accrued for probable losses	8,000,000
Amount of reasonably possible losses, Minimum	0
Amount of reasonably possible losses, Maximum	104,000,000
Loss Contingency, estimate of possible loss									101,400,000
Damages sought amount					4,800,000			103,100,000		11,700,000
Payment awarded to plaintiffs						800,000	89,700,000
Number of claim suit filed							3
Payment to other party for settlement	$ 1,800,000